1. Field of Invention
The present invention relates to modular refractory fiber blanket furnace lining systems.
2. Description of Prior Art
Refractory fiber blankets made from refractory materials such as chromia-alumina-silica, alumina-silica compositions and zirconia compositions have become desirable as furnace insulation because of their ability to withstand high temperatures. The fiber blanket material has been attached in a layered construction arrangement to the furnace wall using attachment structure, as exemplified in U.S. Pat. Nos. 3,523,395 and 3,605,370. Another technique is to fabricate the refractory fiber blankets into modules, as in U.S. Pat. No. 3,952,470, of which applicant is inventor.
While layered refractory fiber blankets and refractory fiber blanket modules are becoming more readily acceptable in the furnace insulation industry, certain problems exist. For example, several types of refractory fiber blankets are available, each having a different temperature rating. Further, the blankets generally increase in cost as temperature ratings increase. It is desirable, however, to use as much lower cost material as possible while making sure that specified temperature insulation limits were met.
A second problem is that of damage to the fiber blanket once installed. For economic reasons, it is often virtually prohibitive in cost to replace a large layered blanket module, which might be from fifty to two hundred square feet in surface area, which has only a relatively small damaged area. However, unless replaced, the damaged area would grow in size.
Other types of insulation structure, such as fibrous batting, in which the layers were bound together by glue, as exemplified in U.S. Pat. No. 2,454,175, were unsatisfactory for several reasons, for example, ease of installation and repair, cost of fabrication and inadequate ability to withstand high temperatures.